Effects of insulin and gastro-intestinal hormones on feeding and plasma insulin levels in sheep.

Infusions of the following hormones were made into the hepatic vein of sheep over periods of three hours: pentagastrin (2.1, 5.0 or 9.9 micrograms/kg), pancreozymin (1.0 units/kg), secretin (2.0 units/kg), insulin (2.1 or 4.3 units/kg). Intake of the concentrate food was depressed by pentagastrin at 9.9 micrograms/kg/3 hr (P < 0.05) and increased by insulin at 4.3 units/kg/3 hr-(P < 0.05) Insulin levels in jugular plasma were unaffected by any of the gut hormone infusions. The liver is suggested as being involved in the control of food intake in sheep.